Controlled balance flow of parallel boiler circuits



Aug. 25, 1942. w. J. BESLER 2,293,929

CONTROLLED BALANCE FLOW OF PARALLEL BOILER CIRCUITS Filed March 29, 1938 I INVENTOR. 147/4 4 IA M J BESL 2 ATTORNEY Patented Aug. 25, 1942 UNHD STATS PAINT OFFIQE CONTROLLED BALANCE FLOW OF PARALLEL BOILER. CIRCUITS William J. Besler, Plainfield, N. J.

Application March 29, 1938, Serial No. 198,678

l5 Claims. ((11. 122-4511) The present invention relates to continuous flow boilers of the once-through type characterized by the absence of headers and drums, and particularly concerns the balancing or equalizing of the flow of the operating fluid through the separate circuits which unbalance the flow and lead to various serious dangers, such as bursting of the tubes, and in any event upset control.

The circulation of operating fluid or water in tubular boilers of this type is maintained at a pressure regulated to the demands of operation. The quantity flowing through each of the circuits, which are of the same area in section, is determined by the speed of flow, and this in turn is dependent upon the resistance encountered in the flow. Since water is not compressible as is steam or a mixture of steam and water, any reliable control of the resistance or the regulation of the Water supply should be primarily responsive to conditions in the liquid or water zone of the circulatory system.

It is, therefore, the object of the present invention to specifically re-apportion and proportion the heating surface so that the majority of the resistance to flow will be in the totally liquid or water zone. In placing the heating surface so that the resistance to flow is substantially in the water zone and is in the region of the coolest gases or in the region farthest from the fire, the further object of obtaining a true counterflow relationship between the heat and the operating fluid is an additional result and benefit.

It is also an object to the present invention to provide a water zone of the heating surface composedof tubing of a smaller area with respect to the other zones thereof so that the greatest resistance to flow will occur in this Zone and be subject to accurate control.

In furtherance of the above, it is also an object to increase the area of the zones progressively from entrance to outlet so that resistance to flow may be likewise progressively decreased as it approaches the outlet and so insure the requisite condition that suflicient resistance to flow will be in the water zone to maintain equal flow through the parallel circuits.

Further objects are to provide a construction of maximum simplicity, economy and ease of assembly, and such further objects, advantages and capabilities as will later appear as the description progresses and as are inherently possessed by the invention itself.

The invention further resides in the combination, construction and arrangement of parts illustrated in the accompanying single sheet of drawings, and while there is shown therein a preferred diagrammatic arrangement, it is to be understood that the same is capable of modification and change and comprehends other details and constructions without departing from the spirit or the scope of the present invention.

Referring in particular to the drawing disclosing the preferred diagrammatic embodiment, there is shown in the single figure a diagrammatic representation of the complete system. The boiler casing of the system is designated as It], and although shown as a horizontal tube type, this is not a feature of the invention as it is equally adapted to any other type of boiler including the vertical form. Inside the boiler casing ll) is located the tubing of the Separate fluid circuits arranged for parallel flow in circuits or channels II to M, inclusive. In the diagrammatic representation, the fluid or water zone, which is the economizer zone, Ila to I la inclusive, is shown as having the smallest diameter, the mixed flow zone llb to Mb inclusive, as having a larger diameter and the superheat zone Ilc' to M0 as having the largest diameter, so that the area increases as the flow progresses from inlet to outlet. It will also be observed that the fluid or water section of smallest area has a greater length than either of the other sections and is so positioned that it is farthest away from the firebox section [5 of the boiler. Also, it is to be noted that the length of the zone decreases as the area increases. These observations are not required conditions. All that is required is that the water zone be of sufficient length and smaller area to bring about substantially the greatest resistance to flow in this zone. Operating fluid is carried to the system by line [6 and distributed at the controlled pressure to each of the circuits II to I4 by the header ll. superheated steam is taken by header I8 and thence by line 20 to accomplish whatever useful purpose is designated.

The operating drive of the control is secured by means of motor 2| connected in a circuit with an energy source or battery 22' and a master understood that any number of parallel circuits switch 23, This motor drives the blower fan 24 may be employed and that the number here located in the air duct 25 which suplies air to shown is for purposes of illustration only. the burner assembly 26 located at the mouth of Under normal operating conditions, water is the firebox i5. supplied to the system by closing the master Motor 2| also may drive the fuel pump 21 which switch 23 which completes the circuit to motor 2| takes fuel from the supply tank 28 and conveys and at the same time initiates fire in the boiler it along the line 30 under pump pressure to the at the burner 26 by circuits and means not here burner assembly 26. shown. Water is pumped from the tank 32 along The same motor 21 may also drive the water the line 33 and since the solenoid of valve 35 pump which always supplies more water than the which is normally open has been energized by boiler can evaporate and forces the supply water the closing of the switch 23, the return line 34 through the system. The how of water from the Will be closed to the flow, and flow will continue, pump 3I' is directed along feed water line 33 therefore, along line 31. Water is supplied at a and when the primary solenoid valve 35 is open, rate which represents a deficiency, or, in other as it is normally, it is returned through lines 34 words, less water than is required by the proporand 36 to the water supply tank 32. Solenoid tion of the fire to produce a desired outlet steam valve 35 is normally open and when open no water condition. This rate of flow may be regulated by is delivered to the boiler and upon being enerthe primary flow control valve 38. The compengized closes so that the water will not be diverted sator 40 in the water feed line I6 keeps the presfrom'the upp1y1ine supply line 33 also branches sure in the feed line at a constant higher pressure into line 31 when the flow in the main or primary than the pressure at 16. For example, let it be supply line I6 is permitted and this flow is adassumed that there is a pressure in the lines 33 justed by the primary water supply valve 38. Inand 3! of 1000 pounds p. s. i. and a pressure of terposed in the water supply line I6 is a compen- 950 pounds p. s. 1; after the orifice of the primary sator 40 which may be spring loaded and set control valve 38. The pressure drop, therefore,

for any desired pressure, as for example at 50 'across the primary orifice or the orifice of the pounds p. s. i. primary control valve 38 is 50 pounds, Also, as-

Line 33 also carries water to the secondary supi sume that the spring in the compensator 40 exerts ply line 4| which is controlled in its fiow by a pressure of 50 pounds p. s, i. If there is an insecondary solenoid valve 42, which is normally a crease in the pressure drop of more than 50 closed but opens when energized in response to pounds in theorifice of valve 33, pressure builds a rise in the outlet temperature. In the line 4| M. up in line 33 and forces the piston of the compenbetween the secondary flow control valve 6 and P sator 40 to compress t spring opening the valve the secondary solenoid valve 42 is a ball check 49a and b eed O l the additional fiow and mainvalve 43 or any other suitable check means. Line tain the required pressure differential. This is 4| branches and forms the normalizer supply line p s d t r e Valve Opening until 45. In the latter line are interposed suitable j e pressure in the line 33 equals the combined control means such as orifice 46, control valve 47 r pressure of the compensator and the pressure at and check valve 43 The normalizer supp1y li the valve orifice 38. In reducing this to a formula, directs the flow to the header 5"5 which disy equals the pressure in line 33 and 0; equals tributes to a plurality of jets 5la to 51d, inclusive t e pressure after the orifice of valve 38 and z each with an orifice 58a to 58d for injection of equals the pressure exerted by the compensator water t t superheat Z0ne Wspring or the pressure required to unseat the Suitably mounted in the outlet end of the cir- Z51 valve 40a then y eq l it plus a at ll times. This cuit are temperature and pressure responsive 3 being ue, the flow can be metered y regulating mechanisms. A thermometer or other heat rethe Valve 33 and the fiOW Of Water j ted in sponsive means is located within the line 29 and prim ry valve to y ount desired. The is so coupled'with the thermomstatic control 5! primary w er supp y n fl ws on hr h line t upon a rise in t e temperature of th super- [6 into header I1 and thence into the parallel heated steam above the control point, the contact ts l l3 and The fact that the pe 52' will be made to close an electric circuit for ena ng con s Call for a deficiency Of ter ergizing solenoid valve 42. Also, the pressure conthrough e p y C cuit results in a rise in trol mechanism 53 is positioned in this area. The the temperature of the p e ted steam in line diaphragm 54 may be t t any pressure 55 20. This riseintemperature through the thermo- Sired and upon decrease in th pressure th MM stat 5| makes contact at 52 and closes an electric the contact at 55 is made to complete an electric circuit Which e es the solenoid of the seccircuit and the control is set up to restore the A y V e 42 Which s normally osed. Feed proper pressure hi system i l adapted Water then comes in from supply line 33 to line for the addition of control means to shut off the p es pwar y hrou h ballcheck valve 43 fire in case f increased temperature or pressure and past the orifice of the secondary control valve above desired1imits 44, and thence into supply-line [6 for a secondary Operation supply of water to the parallel circuits. This mJection of secondary water increases the flow'of In describing the present operation, it is asprimary water and by means of valve 44 and its sumed that upon the starting the position of the orifice, the volume of secondary water may be water level in each of the parallel circuits, i. e. adequately controlled.

ll, l2, l3 and M, will or may not be the same, With the actuating of the secondary control and that during the start-up period, the flow must solenoid valve '42, secondary feed water is likebe equalized and thereafter maintained within wise supplied to the normalizer line 45, which the water zone before it enters the latent heat, passes through orifice 46 to the normalizer conmixed flow, or steam and water zone. It should trol valve 41 through line 45 to header 56 be noted that although the description will be where the normalizer portion of the secondary made with reference to the diagrammatic drawwater is injected by means of injectors 51a to ing which shows four parallel circuits, it is to be 57d through orifices 58a to 5812 into the superheat zone Hie to Me. The orifice M in the normalizer circuit is proportioned so that if valve 41 should be wide open the volume would be limited so as not to inhibit the temperature rise in header l8 and line 2!) and so prevent the requisite supply of secondary water to the system, and consequent undesirable temperature rise before the point of normalizer injection 57a to 51d.

Thus secondary water is supplied not only through the addition of water to the primary flow but also through the normalizer by injections into the tubing nearest the boiler outlet. This supply of secondary water, including the normalizer flow, is proportioned so that it supplies the deficiency of the primary flow and meets the operating requirements. The effect of injecting secondary water near the boiler outlet is to secure rapid response in the operating outlet thermostat in order that this thermostat may be given advance information of the rise of feed water'in the heating circuits; otherwise, the boiler may go into flood condition.

It will be understood that any circuit l I, l2, E3 or M, which has the least water in liquid form will have the least resistance to flow and that water when supplied at the pressure controlled by the compensator in relation to the values fixed in the formula, will tend to fiow into this circuit as the path of least resistance. This, however, is only true where the greatest or the majority of the resistance to flow is maintained in the water zone Ha to I ia. Several features particularly combine to insure such allocation of flow. The length of the tubing prolongs the water zone until equalizing can be accomplished; the progressive increase in area of the sections successively handicaps them as zones of resistance; and the disposition of the water zcne in the coolest portion of the boiler insures that the zone will keep the operating fluid in liquid condition.

Control can only be effected in the economizer or water and latent heat or mixed flow zones, and cannot be attained in a circuit so proportioned that the majority of resistance to flow in each circuit would be in the steam zone or Ilc to Me. If this latter condition were the case, it would then follow that the circuit which had the most steam would likewise have the most resistance to flow, and consequently the circuit having the least water would oifer the path of greatest resistance. Accordingly, water entering the boiler system would choose some other circuit where the resistance to flow would be less, bringing about a condition which might result in water squirting from one of the circuits while highly superheated steam would issue from the circuit or circuits which had tended to starve. Obviously, control of the system would be impossible because of the variations in temperature of the several circuits, and damage would result to those circuits where there was insuii'icient water.

It is also of importance to note that the flow control here disclosed and described accomplishes likewise a controlled counterflow with the portions of greatest heat transference nearest the burner and portions of lowest heat transference farthest from the burner with the appropriate intermediate gradations.

I claim:

1. In a vapor generator of the once through type, a plurality of circuits within the generator arranged for unbroken parallel fiow and for receiving pressure liquid at the inlet and delivering vapor at the outlet, said circuits each being arranged in zones, each successive zone being of increased cross-sectional area from inlet to outlet, said zones substantially corresponding to the liquid zone, the mixed liquid and vapor zone and the superheat zone.

2. In 'a vapor generator of the once through type, a plurality of circuits within the generator arranged for continuous parallel flow and for receiving pressure liquid at the inlet and delivering vapor at the outlet, said circuits each being arrangedin zones corresponding to the liquid zone, the mixed liquid and vapor zone and the superheat zone, e'ach successivezone being of increased cross-sectional area from inlet to outlet, and the length of the zone varying inversely with the area.

3. In a steam generator of the once through type, including a plurality of circuits arranged for uninterrupted parallel flow of water where pressure water at an operating deficiency is received at the inlet and superheated steam is delivered at the outlet, each circuit having a liquid zone, a mixed liquid and vapor zone and a superheat zone progressively increasing in cross-sectional area from zone to zone, the liquid zone being smallest, the mixed liquid and vapor zone being larger and the superheat zone being the'largest in area, and combined pressure drop and flow equalizing means for injecting secondary water to supply the operating deficiency into the system and normalizer water into the superheat zone.

4. In a vapor generator of the once through type, a plurality of circuits within the generator arranged for uninterrupted parallel flow and for receiving pressure liquid at the inlet and delivering vapor at the outlet, said circuits being arranged in a plurality of the zones wherein the pressure drop decreases from zone to zone and wherein said zones substantially approximate the liquid zone, the mixed liquid and vapor zone and the vapor zone.

5. In a vapor generator of the once through type, a plurality of circuits within the generator arranged for parallel flow and for receiving pressure liquid at the inlet and delivering vapor at the outlet, said circuits being arranged in a plurality of the zones wherein the pressure drop decreases from zone to zone and the resistance to flow is substantially maintained in the liquid zone and wherein said zones substantially approximate the liquid zone, the mixed liquid and vapor zone and the vapor zone, means for supplying primary liquid to the system at an operating deficiency and means operative in response to temperature and pressure at the outlet for supplying secondary liquid to meet the deficiency.

6. In a vapor generator of the once through type, a plurality of circuits within the generator arranged for parallel flow and for receiving pressure liquid at the inlet and delivering vapor at the outlet, said circuits being arranged in a plurality of the zones wherein the pressure drop decreases from zone to zone substantially maintaining the greatest resistance to flow in the liquid zone and wherein said zones substantially approximate the liquid zone, the mixed liquid and vapor zone and the vapor zone, means for supplying primary liquid to the system at an operating deficiency and means operative in response to temperature and pressure at the outlet for supplying secondary liquid to meet the deficiency both to the inlet end and to the vapor zone, said supply means for the vapor zone being restricted so that if wholly open the volume of liquid supplied would not inhibit a temperature rise in the flow thereafter.

7. In a vapor generator of the once through type, a plurality of circuits within the generator arranged for parallel flow and for receiving pressure liquid at the inlet and delivering vapor at the outlet, said circuits being arranged in zones corresponding to the liquid zone, the mixed liquid and vapor zone and the vapor zone, means for maintaining substantially the greatest resistance to flow in the liquid zone, means for supplying the primary pressure liquid at an operating deficiency and means responsive to the temperature and pressure of the vapor at the outlet for supplying secondary liquid to meet the deficiency.

8. In a vapor generator of the once through type, a plurality of circuits within the generator arranged for parallel flow and for receiving pressure liquid at the inlet and delivering vapor at the outlet, said circuits being arranged in zones corresponding to the liquid zone, the mixed liquid and vapor zone and the vapor zone, means for maintaining substantially the greatest resistance to flow in the liquid zone, means for supplying the primary pressure liquid at an operating deficiency and means responsive to the temperature and pressure of the vapor at the outlet for supplying secondary liquid to meet the deficiency, said means supplying secondary liquid both to the inlet and to the vapor zone.

9. A method of operating a steam generator having a plurality of circuits arranged therein for parallel flow receiving water at one end and. heated to deliver superheated steam at the other, which comprises the maintenance of the greatest resistance to flow within the totally water zone and increasing the cross-sectional areas of the mixed flow and superheat zones to prevent resistance to flow.

10. A method of operating a steam generator having a plurality of circuits arranged therein for continuous parallel flow receiving water at one end and heated to deliver superheated steam at the other to balance or equalize the flow in the various circuits, which comprises the reducing of the cross-sectional area of flow in the water zone in order that the greatest resistance to flow will occur in this zone where the pressure is constant.

11. A method of operating a vapor generator having a plurality of circuits arranged therein for uninterrupted parallel flow receiving liquid at one end and heated to deliver vapor at the other for controlling the balance or equalization of the flow in the varying circuits, which comprises the maintenance of the greatest resistance to flow within the liquid zone and decreasing the pressure drop from zone to zone to prevent resistance to flow.

12. A method of operating a vapor generator having a plurality of circuits arranged therein for parallel flow receiving liquid at one end and heated to deliver vapor at the other to balance or equalize the flow in the various circuits, which comprises the maintenance of the greatest resistance to fiow within the totally liquid zone, decreasing the pressure drop from zone to zone to prevent resistance to flow, supplying primary liquid at an operating deficiency and supplying secondary liquid to satisfy the deficiency in response to the temperature and pressure of the vapor at the delivery end.

13. A method of balancing or equalizing the flow of operating liquid in a steam generator having a plurality of uninterrupted parallel circuits therein comprising the steps of maintaining the greatest resistance to flow in the circuits within the totally liquid zone in said circuits and within the said generator.

14. A method of balancing or equalizing the flow of operating liquid in a vapor generator having therein a plurality of uninterrupted parallel circuits comprising the steps of maintaining the greastest resistance to flow within the totally liquid zone in said circuits within said generator and maintaining the totally liquid zone in the region of the coolest gases farthest from the fire.

15. A method of balancing or equalizing the flow of operating liquid in a vapor generator having therein a plurality of uninterrupted parallel circuits comprising the steps of maintaining the greatest resistance to flow within the totally liquid zone in said circuits within said generator and maintaining true counter-flow relationship between the operating liquid and the heat.

WILLIAM J. BESLER. 

